1. Field of the Invention
This invention relates generally to hypodermic needles which are adapted to inject substances into humans and animals and/or to withdraw specimens therefrom, and more particularly to a hypodermic needle having a protective sheath for shielding the needle during use, storage, and disposal.
2. Brief Description of the Prior Art
The shielding of hypodermic needles is of critical concern to health practitioners from the standpoint of both handling the needle and the disposal of used needles. Accidental exposure or puncture by the sharp end of the needle can have very serious and even fatal health consequences. For example, the needle may be contaminated with diseases such as hepatitis or A.I.D.S. It is therefore desirable that the needle be shielded immediately after use with a minimum of handling and be disposed of in a reliable and efficient manner to provide protection from accidental puncture.
There are several patents which disclose apparatus for shielding a hypodermic needle against accidental puncture and for covering the needle for disposal. Most of these patents teach devices which are mounted on the dispensing syringe, and the shielding member remains in a position covering the needle after use.
A major disadvantage with these shielding devices is that the entire dispensing syringe must also be discarded along with the needle. Disposal of hazardous waste in health facilities is a precise science. Special containers are used and rigid guidelines are followed in disposal operations. Often the practitioner is charged by the weight of the hazardous materials which are to be disposed of. The cost of special handling of hazardous material is passed along to the patient. It would be desirable to provide a device which would allow the needle to be separated from the syringe whereby both members may be disposed of separately.
U.S. Pat. Nos. 3,370,588, 3,405,713, and 4,747,835 are examples of removable needle shielding devices which are manually removed and replaced by pulling them completely off of the syringe or needle base. These devices have the disadvantage of losing the shield when removed and leaving the needle exposed and also present a risk to the person doing the handling when replacing the shield.
Sampson et al, U.S. Pat. No. 4,425,120 discloses a shielded hypodermic syringe having a tubular sleeve which slides on the barrel of the syringe and is movable from a forward shielding position to a rearward non-shielding position and utilizes slots in the sleeve to lock it n either position. This device requires manually moving the shield to the shielding position and consequently there is substantial risk to the person doing the handling and the possibility of the shield being accidentally left in the non-shielding position.
U.S. Pat. Nos. 4,655,751, 4,702,738, and 4,702,739 are examples of other shield devices which are mounted on the syringe rather than on the needle and which require manual movement of the shield to the extended position. These patents also inherently present a risk to the person doing the handling and the possibility of the shield being accidentally left in the nonshielding position.
Laico et al, U.S. Pat. No. 4,804,372 teaches a protective sheath which is mounted on the hypodermic needle base. The shield device comprises a pair of telescopic tubular shields slidably mounted to the needle base. Detent locking members lock the shields in a non-retractable extended position. This device also requires manually moving the shields to the shielding position with the resultant risk to the person doing the handling and the possibility of the shield being accidentally left in the non-shielding position.
U.S. Pat. Nos. 3,073,306, and 4,816,022 are also examples of other shield devices which are mounted on the needle rather than the syringe but still require manual movement of the shield to the extended position. These devices also inherently present a risk to the person doing the handling and the possibility of the shield being accidentally left in the non-shielding position.
White, U.S. Pat. No. 2,876,770 discloses a shielded hypodermic syringe which hides the needle from view and also shields the needle after use. The shield device comprises a pair of telescopic tubular shields urged apart by a compression spring. One end of the inner member is mounted on the syringe and its other end is provided with a stop flange. The outer member is slidably received on the inner member and has a ring-like retainer mounted at its rearward end having an inwardly facing flange which engages the inner member flange in the normally extended position. The retainer ring exterior has a semicircular step portion which extends rearward. When the outer member is rotated to one position, the step portion will engage the stop pin, and when rotated to another position step portion will engage end of the syringe whereby selective exposure of the end of the needle is controlled. This device does not provide for positive locking of the outer member in a non-retractable extended position with the resultant risk of accidental retraction of the shield during handling or disposal.
Hall, U.S. Pat. No. 4,416,663 discloses a shielded, self sterilizing, hypodermic syringe comprising a pair of telescopic tubular members having a compression spring disposed therebetween. The outer member is snap fitted onto the needle and the inner member is slidably mounted within the outer member to extend outwardly beyond the forward end. The inner member is an enclosed capsule containing sterilizing material and has perforated ends. When the capsule is pressed against the skin the needle will penetrate and pass through the sterilizing material to exit the outer end on its forward motion and when the needle is withdrawn the spring will position the capsule such that the needle tip is disposed within the sterilizing material. This device also does not provide for positive locking of the outer member in a non-retractable extended position with the resultant risk of accidental retraction of the shield during handling.
The present invention is distinguished over the prior art in general, and these patents in particular by a sheathed hypodermic needle having a retractable tubular sheath slidably mounted on its forward end and movable relative thereto between a rearward retracted position exposing the front end of the needle and a forward protective position enclosing the front end of the needle. In one embodiment, a spring within the sheath urges the sheath to the forward protective position enclosing the front end of the needle. The rear of the sheath cooperates with pins on the needle to engage the pins upon relative rotation in one direction to allow rotation as a single unit to connect the needle to fluid ejection or withdrawal members. Relative rotation in the opposite direction disengages the pins to allow the sheath to be moved rearward causing the front end of the needle to protrude beyond the front end of the sheath and to lock the needle and sheath together upon further relative rotation in the same said opposite direction to disconnect and dispose of the needle without inadvertent injury by contact with the needle. Another embodiment has protrusions on the needle and a retractable sheath slidably mounted on the needle and movable between a rearward retracted position exposing the needle front end and a forward protective position engaging the protrusions and covering the front end of the needle. A further modification has a tubular catheter slidably received on the needle for hypodermic penetration therewith which is removably connected to the sheath whereby when the sheath and needle are removed from the catheter only the catheter remains in place.